abstract class Animal {
    abstract void shout();

}
class Cat extends Animal {
    public void shout() {
        System.out.println("喵喵......");
    }
}
class Dog extends Animal {
    public void shout() {
        System.out.println("汪汪......");
    }
}
class Example15 {
    public static void main(String[] args) {
        Animal an1 =new Cat();
        Animal an2 =new Dog();
        an1.shout();
        an2.shout();
    }
}